Present and future of diagnostic ultrasound

An adequate amount of blood supply is necessary for the proper functioning of all body organs as blood carries all the nutrients and oxygen that our body needs to stay healthy. Various diseases cause an impaired supply of blood to the organs. The measurement of the blood flow can therefore provide essential information for the diagnosis of diseases. Since changes in blood flow occurs with the very initial stage of disease, with a fast, reliable and noninvasive blood flow measurement technique, the physicians would be provided with new options for early disease diagnosis. Beginning with brief overview of early methods of blood flow measurement, this article reviews the recent blood flow measuring techniques in detail and ends with suggestions for future research in related areas.

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Measuring blood flow: techniques and applications - a review

Telemetering blood flow velocity and ECG during exercise

Evaluation of blood flow velocity waveform in common carotid artery using multi-branched arterial segment model of human arteries

The cardiovascular system is described by parameters including blood flow, blood distribution, blood pressure, heart rate and pulse wave velocity. Dynamic changes and mutual interactions of these parameters are important for understanding the physiological mechanisms in the cardiovascular system. The main objective of this study is to introduce a new technique based on parallel continuous bioimpedance measurements on different parts of the body along with continuous blood pressure, ECG and heart sound measurement during deep and spontaneous breathing to describe interactions of cardiovascular parameters. Our analysis of 30 healthy young adults shows surprisingly strong deep-breathing linkage of blood distribution in the legs, arms, neck and thorax. We also show that pulse wave velocity is affected by deep breathing differently in the abdominal aorta and extremities. Spontaneous breathing does not induce significant changes in cardiovascular parameters.

Respiratory-induced hemodynamic changes measured by whole-body multichannel impedance plethysmography.

We have developed a blood flow velocimeter to measure maximum blood flow velocity (MBFV) in carotid, brachial and femoral arteries simultaneously by using a Doppler ultrasound technique This measurement system is based on a continuous wave Doppler ultrasound method with two semicircular piezoelectric (PZT) transducers, one continuously transmitting ultrasound, and the other continuously receiving the echoes This report is to investigate variations of MBFV in 3 arteries of 5 healthy normal male volunteers during passive postural changes in supine, 90 degrees head-down-tilt (HDT) and 90degrees head-up-tilt (HUT) respectively As a result of these measurements, we could confirm that MBFV in those arteries especially in brachial and femoral are increased by supine to HDT posture and are decreased by supine to HUT posture But, it's just changed a little in carotid artery An increasing and a decreasing in MBFV are expected to be an effect of venous pressure and a constant MBFV in carotid artery is caused a cerebral autoregulation

Variations of the Maximum Blood Flow Velocity in the Carotid, Brachial and Femoral Arteries in a Passive Postural Changes by a Doppler Ultrasound Method

We investigated the common carotid artery (CCA) blood flow velocity in 5 healthy sedentary subjects using continuous wave (CW) Doppler ultrasound velocimeter which developed in our laboratory. The present study aimed to investigate non-invasively the effects of a short-term 4 week aerobic training program on the resting CCA blood velocity waveforms and heart rate. The CCA blood velocities were measured for 3 minutes at resting sitting posture with synchronized measurement of electrocardiogram (ECG) and brachial blood pressure (BP). Training exercise significantly enhanced all blood velocity waveforms with decreasing of heart rate. Systolic blood pressure (SBP) changed with training in the young sedentary subjects, but there is not significant change in diastolic and its mean blood pressure. The evidence of improvement in training was reinforced by a significant reduction in peripheral vascular resistance and improvement in vagal function. We conclude that short-term training improves cardiovascular and autonomic function in these subjects, and training effect may be simply evaluated using the non-invasive measurement system of blood velocity in CCA.

Changes in the common carotid blood velocity waveform for exercise training

To know a characteristic of the whole blood cardiovascular system, we need to measure the blood flow respond in relation to giving exercise stress to our body. In this paper, we have developed a noninvasive device to be able to measure blood flow velocity in the carotid during physical exercise by using a Doppler ultrasound method. The purpose of this study is that we focus attention on measured maximum blood flow velocity (Vmax) and analyze the physiological function change of blood flow dynamic system in the carotid during physical exercise by a cicycle-ergometer. Generally biological information (eg. brain wave) is known as a nonlinear signal. Correspondingly, neural networks (NN) have recently been known as one of nonlinear signals analysis tools. For such occasions, we suggest that we identify Vmax (non-linear time series) variation using an MA (Moving Average) model associated with back-propagation (BP) algorithm. After simulating Vmax variation, we found out that the neural network (BPNN) can capture the regularity from that, and the adaptive changes of the system dynamics are evaluated in the connection-weight-space (CWS), a kind of internal representation of the trained network. As a result, we can abstract respective characteristic from that. This technique is expected to estimate a physical exercise quantitatively and rehabilitation training.

Detection of a maximum blood flow velocity variation in the carotid artery during physical exercise using BPNN

Dynamics of blood flow in vivo vary with cardiovascular disease. To examine dynamics change of blood flow is useful in the prevention of cardiovascular disease. This study is aimed to investigate the common carotid blood velocity (CCBV) in the cardiac patients. It was performed in 14 cardiac patients (mean ± SD age 68.5 ± 8.3) and 8 healthy subjects as control (age 22.8 ± 1.6). The variations of CCBV were measured using a telemetry blood flow velocimeter system in real time display that was completely developed in our laboratory. This measurement system is based on continuous wave (CW) Doppler ultrasound using two transducers which one is for transmitting and the other one is for receiving. In the report, data were measured for 90 seconds at the rest sitting posture with synchronized measurement of electrocardiogram (ECG) signal. Electromechanical delay (Δt) between ECG signal and CCBV were measured from time of R-wave (Tr) to time of the peak systolic blood velocity (T1). The Δt was 0.169 ± 0.008 s in the healthy subjects. While, the Δt was 0.131 ± 0.016 s in the hypertensive. The delay decreased relatively in the hypertensive. It was coincided with decreases of the magnitude of the peak of diastolic velocities. Furthermore, an acceleration index (AI) and a peak systolic velocity (S1) had correlation in the cardiac patient. The value of AI and S1 decreased particularly. The results suggest that the Δt is affected by arterial properties that may be related to arteriosclerosis.

Measurement and Analysis of Carotid Blood Flow and ECG in Cardiac

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Papers

Variations of the Maximum Blood Flow Velocity in the Carotid, Brachial and Femoral Arteries in a Passive Postural Changes by a Doppler Ultrasound Method

Changes in the common carotid blood velocity waveform for exercise training

Detection of a maximum blood flow velocity variation in the carotid artery during physical exercise using BPNN

Measurement and Analysis of Carotid Blood Flow and ECG in Cardiac